6GW8 find

[Frankenamp]

I was trying to find a smaller amp and found this one on fleabay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=350226856752

I think it has better possibilities than a couple of overpowered organ amps I found for real cheap (but don't have the heart to desicrate...yet: mystery 4-6L6, & a Conn 2-6l6 + 4-12V6 monster...)

It has a 6EU7, and a 6GW8 combo tube, with a 6X4 recto, I poked around a little and didn't find too much- anyone have a schematic for that lube lineup or is it in uncharted territory? (don't have it yet, but should soon depending on the mail...) I'm sorta thinking something a little champish since it seems to be a SE with that triode/with a built-in EL84?

[jjasilli]

6EU7 is supposedly a hi-fi version of the older versions of the 12ax7.  6GW8 is a triode and pentode in one bottle.  The pentode side is your power tube.  Your amp does appear to be single ended.  So you have a total of 3 gain stages; or maybe the makings of a tremolo circuit, whatever.  The Bogen CHB-20 uses these same tubes, though it's PP with SS rectification.

What is that rectangular component on the right???  I have a Cordovox tone generating amp which is full of those things.  RF inductor?

[Shrapnel]

6EU7 is supposedly a hi-fi version of the older versions of the 12ax7.

Yepp, the 6EU7 is basically the 12AX7... single voltage heaters, different pinout, "hi-fi" version is what I've heard too. However they do make a good preamp tube... just be ready to pay extra (The Hi-Fi Tax) if you need to replace them though. I've got them in one amp I rebuilt from a PA head. (Three of 'em were in it along with a couple of EL84s and one EZ81.)

(the modded head is my avatar.)

[PRR]

> a schematic for that lube lineup or is it in uncharted territory?

Don't look for tube-types, look for "functions".

> has a 6EU7, and a 6GW8 combo tube

Re-bottled 12AX7, plus a bottle with a single AT7/AX7-like triode and a half-size EL84.

If we knew this was a gitar amp, or a hi-fi amp, there are not THAT many ways to Do It.

> "I believe this amp came from a hi-fi console."

He can believe what he likes; that has to be a tape-deck chassis. Note the "radio IF can", actually a supersonic bias oscillator tank. Note the 7-pole 2-throw switch: this re-jiggers all the connections between Record and Play.

The tape-head preamp is massively dull (to compensate the tape-head's shrill). In Microphone it may be suitable for gitar, but when using Mic it would normally kill the speaker power-amp (anyway it is probably re-purposed for bias osc.).

So I hate to say it, but: rip it apart. Leave the power supply, that's fine. So is the power pentode's cathode connection (probably). But most of the rest.... it is easier to copy a Champ than to work out what-all is going on in that massively switched rat-nest.

[jjasilli]

PRR:  Note the "radio IF can", actually a supersonic bias oscillator tank.

So that's what those things are.  I was hoping ypou'd chime in on this one.  Thanks again!

BTW:  If anyone needes some supersonic bias oscillator tanks, I've got a few to spare.

[Frankenamp]

Ahhhh! that multipole swich had me scratching my head, I'm glad to have that answered. It seemed like a lot of stages for a otherwise simple single end amp, but record/play functions seem to make sense.

SO:   can the supersonic can, misc switches, and tape recorder specific folderol, should be enough preamp section to add a tone stack?  Any idears to reverse engineer and or plagerize so I can 'KISS'. Thinking about making a small case for it, or sticking it in my 'breadbox' cabinet... with an old Altec 12" biflex driver.


EDIT: I went through a box of tubes and found some interesting ones after separating out the TV tuner peanut tubes, and found the following:
3- 6J6; 2- 6AU6; 2- 6SN7GT; 2- 6K6GT; 1- 25L6; 1- 5U4GB...
in addition to an assortment of 12AX7's 12AU7's couple pair 6L6's (one set bran' new), and a quad of 12V6's from a Conn Organ amp carcass that looks so nice inside that It may be a mortal sin to desecrate... it has the oddball 12V6's and an 0A3 75V gas regulator tube which has me wondering what it was for?  (back to the question at hand) Any of the 6J6's or 6AU6's (or others) possibly sub into the 6GW8 circuitry with beneficial results? or will I need more/different Iron?

[Frankenamp]

Gonna be waiting for mister postman with my impliments of reconstruction in hand... <<anticipation>>

[PRR]

> enough preamp section to add a tone stack?

You got way more than you need for a small amp with tone controls.

> Any idears to reverse engineer and or plagerize so I can 'KISS'.

Steal the AA champ. 1/2-12AX7 preamp (use 6EU7), tone volume, 1/2-12AX7 driver (use 6EU7), 6V6 (use the big-end of 6GW8).

The preamp-driver system is just like AA-Champ except the pin numbers.

The power section: keep the chassis's OT and the 6GW8, use bias values from page 3 of 6GW8 data. Power output is 2.8 Watts; down from Champ but this is all the existing PT and OT can do (and it would be silly to re-iron this pretty chassis, 2.8 Watts can make good sound in a good speaker). The 6GW8/ECL86 is in production, so you need not fear to rack up thousands of hours.

Leave the AA-Champ's 22k? NFB resistor where you can change it. Do 5K for tight clean tone, 47K or open for loose lively tone.

This leaves a "leftover triode". We could find it something to do, but part of the Art of design is NOT having anything un-necessary in the way.

That 110V accessory outlet: remove-discard it, or glue plastic over it. When new they had a high risk of prong-chassis shorts because there is so little clearance between slot and chassis, and people plug-in violently; when Polarized plugs came out, they became a Very Bad Thing because the wide-prong is sure to shatter the socket.

The acc 110V outlet on the same face with controls is odd. I'm now thinking a semi-industrial tape deck. Language Lab, or airport announce system.

[jjasilli]

This leaves a "leftover triode". We could find it something to do, but part of the Art of design is NOT having anything un-necessary in the way.

OK, but I'm thinking a cascading gain stage, or tremolo for the "leftover triode".

If there's not a lot of room for pots, then the Big Muff tone circuit uses only 1 pot, doing a good job of emulating the the 2 or 3 knob FMV tonestack.

[Frankenamp]

Found This:  http://www.r-type.org/static/ecl86.htm

but it has a single pentode for the preamp

Here is a phonograph amp schemo:   http://www.cadillac.demon.nl/images/scan.jpg

Is this paydirt? http://licho.rowerpower.org/gitara/practic2_lite.gif
didn't find much under 6GW8, but ECL86 gives better results...

Feedback please

[billcreller]

  The 12V6s were common in car radios after the switch to 12 volt systems in the mid 50s. The solid state radios came along soon after I believe.  I know Delco and Bendix radios used those.

[Frankenamp]

And on Kendrick's 'Hip Vintage Amps' pg 437 there is a magnatone 411 schematic with the appropriate 6GW8 output tube... and a 6AV6 preamp

The AB764 Bronco amp looks intresting, as does the AA 764 Champ  (thanks, PRR!) Now I gotta wait for the postman to check the exact components and see exactly what I have. I might read through the German articles, having a spouse that's an ex army intelligence German translator spook may prove useful after all...

[PRR]

> Feedback please

 'KISS'
 
Your 1st and 2nd plans are not guitar amps. The 3rd one "is", but gosh what a lot of stuff!!

You know the chassis PT, rectifier, OT, and the pentode of the ECL86 were MADE to push a loudspeaker. They are all the right size for each other: voltage, current, power. The only thing you have to do for your Power Stage is un-ravel the REC/PLAY switching (the speaker-amp was probably muted in REC). Keep the cathode resistor the same; it's right for that tube, voltage, load.

After that: tube is tube. The power end of the ECL86 is just a small (half-size) EL84, which is just a euro-flavor hi-gain 6V6. You CAN use any standard "one 6V6" front-end, and paste-in the smaller ECL86 power section in place of the 6V6.

Among well-respected one-6V6 amps with full tonestack, the AA-Champ is a fine example, good as-is and amenable to many well-known Fender-amp tweaks. And a lot more KISS than this many-parts new-school "licho".

My plan leaves ECL86 triode idle. This is not Little League. Not every kid has to play. Connect pins 1, 2, 9 to ground.

> I'm thinking a cascading gain stage

'KISS'. Or follow the "licho".

> or tremolo for the "leftover triode".

The AA-Champ with trem injects trem signal in the driver cathode. To do this, it needs an oscillator AND a buffer, to pump about a mA of current into the low-Z cathode.

The problem with ALL single-ended trem schemes is thump. You may have 10V of guitar and 100V of sub-sonic. You need significant filtering before your next stage or it just distorts the thumps. Some low-level trems run a 3-stage C-R-C-R-C-R low-cut filter after the stage where trem is injected, before the next stages. The AA-Champ w/Trem has only the one C-R and the OT low-cut.

Push-pull amps often inject trem at the grids of the power tubes. This may need less current, sometimes done without a buffer. With push-pull, the thump cancels, is much less of a problem. With SE, it is a problem. I have seen it done, but more often in some earlier stage so there is more low-cut between the tremmed stage and the output.

And thinking too hard about this violates Franken's 'KISS' idear. Given a KISS SE amp, you are almost certainly better-off with a $49 trem pedal.

Yes, 12V6 is -exactly- 6V6 with a 12V heater. However it was not so common in car radios as 12AQ5, which is a 250V 6V6 in a 7-pin mini bottle.

[Frankenamp]

> Feedback please

 'KISS'
 ... ...
Your 1st and 2nd plans are not guitar amps. The 3rd one "is", but gosh what a lot of stuff!!
... ...
You know the chassis PT, rectifier, OT, and the pentode of the ECL86 were MADE to push a loudspeaker. They are all the right size for each other: voltage, current, power. The only thing you have to do for your Power Stage is un-ravel the REC/PLAY switching (the speaker-amp was probably muted in REC). Keep the cathode resistor the same; it's right for that tube, voltage, load.

After that: tube is tube. The power end of the ECL86 is just a small (half-size) EL84, which is just a euro-flavor hi-gain 6V6. You CAN use any standard "one 6V6" front-end, and paste-in the smaller ECL86 power section in place of the 6V6.
... ...
And thinking too hard about this violates Franken's 'KISS' idear.

Yeah, I know, but you know how it is when you have a new toy in the mail :hello2: I get excited and start lookin' fer new and creative ways to re-invent the wheel. I'm sure that the champ is the way to go, and that's what I'm planning on doing. I just get curious what can be done with an extra triode...   Looking down the road, If the ECL86 needs replacing, can I swap it out for an EL84 or 6(a/b)q5 if I simply rewire the socket?  (I know, git the dang thang delivered and Champerized first, and then worry about what if's...) :evil6:

[Frankenamp]

Mister Postman left a little something on my doorstep... gonna go play with my toys a bit... tag on side has a number... gonna abuse Mister Google.... (Oh Noooooooo) 

[Frankenamp]

The tag sez: "456.94440 Sears Roebuck & co. USA and Simpsons-sears limited.

looks to be in fair to pretty decent condition. The bias osc coil-can looks to be hooked to pin 2 (triode cat) of the 6GW8, pin 1 (triode grid) gord via a 38k resistor and a 4nf ceramic cap to what I assume is the head connection to a black wire across the chassis to one of the major ground points at the base of the cap can. Pin 9 (triode plate) connects to the 20 mfd 300V tap of a multicap can, and a 33nf connects to another ground point near the cap can... I assume these are part of the bias oscillator circuit? (and can be safely removed)
 
Almost all the caps are the little ceramic disc caps there are four strip scattered throughout the chassis- and that monster multipole switch, a red and a clear neon lamp... the volume and tone controls are concentric pots. I'm considering replacing the 6EU7 with a 12AX7 (same base- different pinout) and keeping the 6EU7 for another day (less confusion with the layout) All I need to do there is unsolder pin 3 from the chassis, and move the heater pins to 4,5, & 9.

I'm getting crosseyed trying to figure out things as they are... out with the soldering iron and vacuum bulb! things will be soon be less confuzzeling.       

[Frankenamp]

Vacuum bulb dinna suck fer (fill in yer favorite expletive). So, I raided the table for a soft-serv diameter soda straw that just happened to be in the wrong place at the right time... now I'm gonna have to dust out the little flakes of solder dust that now decorate the inside of said chassis. Big multipole switch is gone, along with half of what needs to be gone from the 6EU7-soon to be 12ax7 tube socket. Damn, there are a lot of those little ceramic disc caps- the sight would have been enough to give the average audiophile tinnitus! What is the reason for having two half-meg resistors between each of the mains (house current) lines and the chassis? Also, the heater wires are daisy-chained a ring... no not quite- the 6GW8 and the 6X4 have heaters in parallel, but the 6eu7 takes one side of the heater from pin 4 of the 6GW8, (to pin 1); the other pin (2) comes off the 6X4's pin 4 through a 5R,5W brown ceramic resistor. It's still parallel, but through the resistor, whats that all about?

[PRR]

> reason for having two half-meg resistors between each of the mains (house current) lines and the chassis?

That's stupid. I've seen it in mid-1960s gear. Very annoying on stage. Remove resistors, install 3-pin power cord.

> through a 5R,5W brown ceramic resistor. It's still parallel, but through the resistor, whats that all about?

Dropping a preamp tube's 6V heater to 5.5V -may- reduce heater emission and hum. I have never found this to be true, but several designers did it routinely. If you keep the tube, leave it alone. If you convert to 12AX7, just wire normally.

[jjasilli]

Angela loves vintage ceramic caps (not new ones).

[zapped]

Is a 6.3V heated recto. tube better/worse or make for less expensive manufacturing cost vs. recto. tube with 5V heater?

[Frankenamp]

Cat bypass is .001 uF which is a strange value, and the resister is 222 ohms, looks to be a 1/2 watt. (shematics range from 170-330 ohms) is this a normal value for this function? (most I have seen are the usual 25u/25v electrolytics never seen a ceramic in this position)

Zapped: I would assume that the 6.3v rectos are a cost cutting measure- one less winding to make on the transformer... I'm sure PRR can enlighten us as to why there is/are a different and/or separate heater winding on most tube amps! And what the reasoning is between 5 and 6.3 volt heater voltages- has to be somthing more than tradition and 'common practice', one would think?

[Frankenamp]

Angela loves vintage ceramic caps (not new ones).

OK, I'll bite- why?

[PRR]

> what the reasoning is between 5 and 6.3 volt heater voltages- has to be somthing more than tradition and 'common practice', one would think?

Filament voltage should be "low", so you can use thick sturdy filaments, and in wall-power to reduce AC radiation. Yet not too low voltage, because you need a certain power, and then low voltage means high current and fat leads. That still leaves a wide range to throw darts at.

5V (and 2.5V, and 4V) is just plain tradition and common practice.

6.3V is the nominal voltage of a 3-cell lead-acid battery such as most cars had back in the day. US tubes went 6V around 1930, because you could sell them to car-radio and also for wall-power work. British cars did not have radios, and wall-radios used 4V heaters up until WWII, when the rise of jeep-radio and need to standardize with overseas sources got them onto 6.3V types.

In the rectifier... it depends. HIGH-voltage heater-cathode insulation is costly and inefficient. Big systems used naked filaments with dedicated winding. However in small systems the added cost for heater insulation might be less than the cost of a winding. So you find 6X4 in preamps, tuners, tapedecks; and 5V rectifiers for anything bigger. It is simple penny-counting.

Except in car-radio. Here, 6.3V is cheap, anything else is very costly. They got 250V with a DC-AC buzzer and a step-up PT, but then needed a rectifier to make that AC into DC. And unlike a wall-powered PT, a rect-heater winding is NOT cheap (actually, the excess capacity in the buzzer). 300V of heater insulation in a 6.3V rectifier was the best option. (Until improved buzzers which also buzzed AC back into DC.)

Pre-cars, a lot of wall-power tubes were 2.5V. Just tradition.

I wonder if 5V rectifiers were using-up excess 2.5V filaments when cathode-tubes all went 6.3V.

4V -may- really be 2 lead-acid cells.

There are a heap of "1V" "2V" and "3V" tubes. Don't assume. Some are made for dry-cell batteries, some are made for lead-acid cells. Read the spec, don't go by type-number.

[jjasilli]

Angela loves vintage ceramic caps (not new ones).

OK, I'll bite- why?

Because of the way they sound.  This is comprised of 2 elements:  that the tone is desrirable; AND that it has a true vintage quality. 

[Frankenamp]

This is the intresting part: I've removed most of the parts except for the Vol/tone/power switch concentric stacked pot, the tube sockets, and the heater CT resistors. For space reasons, I'm wondering whether to replace the RCA jack with a 1/4" phone jack or just leave it be. While I'm dithering about that, and whether to use one or two input jacks in the front panel, (plenty of holes now that the monster switch and 110v accessory  outlet are gone) I'm going to introduce the exterior to mssrs. steel wool & simichrome, and the interior to mister sandblaster... On a whim, I gutted the cap can and am looking to stuff 3 smallish 20uF caps inside for looks- and because the chassis is a mere 1.22" deep. For this reason, I'm gonna forgo the turret board and try my ham-hands at point to point: there are 4 terminal strips already mounted with rivets and large dollops of solder (so the middle terminal of each is a ground point) with 4 (power connections) 5,7, & 8 terms respectively. Once I get that done, I'll scan and post the prospective layout so that those with many moons more experience can save me from more newbie mis-steaks. Now, off to work, and hopefully the hardware store will have some miniature grommets to replace the old ones on the preamp tube's shock mounting...

[Frankenamp]

I have two new best friends: Mister Sandblaster, and Mister 4/0 steel wool. Simichrome ain't too shabby too,  My toy cleaned up real purty. the fun part now is gonna be finding 3- 20 uF caps to stuff in a 1.375" cap tube, gonna be tight!

[Frankenamp]

Here's a possible layout I scribbled up- finally got the scanner to see the pencil and not the graph paper... Hopefully it's legible!

Please look it over and see if I haven't made any henious mistakes

I have a couple of neon lamps (red/clear) from the disassembly/cleanup, what is a good resistor value for a power indicator lamp, and is there a simple way to wire in an overload indicator (or should I jus' fergit about those fancy accessories)?


Thanks!

[Frankenamp]

The tag sez: "456.94440 Sears Roebuck & co. USA and Simpsons-sears limited.

Off the wall question: I heard a rumor that Michael A Simpson Co. (MASCO) did at one time make electronic products for Sears Roebuck mostly for their consoles and radios... Wondering if that critter had it's origins in a Masco factory?

[PRR]

> got the scanner to see the pencil and not the graph paper...

Pencil-marks only look dark. They are really pretty light. And if the light and eye are in the same place, graphite is reflective, very bright. That is seldom seen by humans, but it is how a scanner sees.

I have to take everything above 75% white all the way to black to make pencil-marks pop. The "normal" setting on this adjuster is straight from corner to corner; I've had to yank the lower-left way to the right. I also pull the top-right a bit to the left, because "white paper" is never 100% white (or the scanner leaves some margin).



Pencil mark is spotty, lots of skips. I usually scan high then size-down, sometimes with some smear in between to fill-in the white holes.

Lined-paper, graf-paper, or in this case wrinkled paper (ISO's tone-switch is annoying) makes things worse, because "faint" lines (or wrinkles) are not really different tone than reflective graphite.

> any henious mistakes

There's no 120V fuse? That's the only "OUCH!!!" I see. If something else smokes, it costs less than my unpaid time to tediously check your details.

> neon lamps..., what is a good resistor value for a power indicator lamp

What did they use before??

Ah, one of them is not for 117VAC, but was the "record level meter". For wall-voltage, you can use the same value as the power neon had.

> an overload indicator

Unlike tape, everybody in the room knows when an amplifier overloads significantly. (If it overloads insignificantly, it is not significant.) 

Overload will NOT hurt this amp (as long as it has "some" load).

You could re-insert the "record level" neon and resistor like it was, probably hung on the OT primary. It will be off at silence, blip on fairly loud signal. It can't be precisely calibrated for "onset of overload", like a Crown DC300's IOC lamp; nor should you need such a sissy thing.

[Frankenamp]

My scanner software is pretty primitive- no heuristics, just contrast and lightening/darkening of the test (like a copier)... and a pain in the arse.

The fuse is invisible-  but it's there ;)  I stand well and truely busted on that account!

> neon lamps
  I couldn't trace where the wires were coming and going around the multi-switch. there were actually 3 neon lamps: two (red/clear) on the panel, and one wrapped in a plastic tube back inside the chassis not sure why...  I couldn't tell what the supply voltage was, or the resistor value in that confusing mess... so I whipped out the trusty 40W chisel point and made them all all go away, and followed up with a little quality time in the sand blasting cabinet- aside from the PT & OT connections, the chassis is virginal again.
  Anywise, I was wanting to use at least one of the neons for the power indication the overload was gonna be eye candy, but it's probably a violation of the KISS principle.

One other thing I was considering was the mid scoop resistor that will be soldered to the bass pot: I was wondering if I should leave it alone, add a pot or use a pot with a pull-switch to add another resistor (switch off- 50K+ to ground, switch on inserts a 15-20K in parallel resister) for a shallow dip, or classic deep dip depending on the switch being in or out. 

Thanks for the input, I'm trying to get all my over-thinking and worrying done first so when the last few parts show up, I can make solder fumes without too much worry other than the obligitory "will it blow up when I plug it in" anexiety...

[PRR]

Try 270K 1/2W in series with neons on 120V supply.

That's a rough compromise: the little neons come in two power ratings and you can't really tell them apart. 270K will light-up. The low-power bulbs will have short life (many hundreds of hours rather than thousands of hours).

On a low-voltage amp like this, a neon with 270K across the OT primary will blip on loud peaks, before gross clipping happens. They probably scaled the record-head network for this level, told you to adjust for rare blinks. On high-voltage amps, a simple neon will give too much pre-warning to be any use, and will blow-up if the amp is over-driven hard and long.

[DummyLoad]

< (ISO's tone-switch is annoying)

huh? what i did?   

[Frankenamp]

< (ISO's tone-switch is annoying)

huh? what i did?    angel

Ummm sent 'em a rumpled piece of paper to scan (I guess)

<faux over-the-top-hollywood-diva-overreaction>
How could you? Now really, next time you send him a schematic- make sure it's in pen with the ink dry, ironed flat and laminated with the dress edge to the left! How do you 'spect anyone to scan anything like what you did

<standing back with an appearance of guiless innocence>
::polishes halo::

[PRR]

> what i did?

You bought a cheap Bogen.

Normally I love to figure out How Bogen Did It.

This one.... I (not you!) sketched it on paper, turned it this way and that, showed it to the dogs and they couldn't figure it out either.... arg! crumple and toss.

Then Franken mentioned the problem most scanners have with pencil/paper, and I figgered at least I could get that much use out of the wasted paper. Well, scanner doesn't handle wrinkes well either.

NO offense intended.

[DummyLoad]

> what i did?

>>You bought a cheap Bogen.


guilty as charged! although 40 clams + 25 to ship might not be considered cheap in some circles... but now it's an evil little thing.. kind of like those mini robots in transformers movies.

>> Normally I love to figure out How Bogen Did It.

so do i, that one made my head hurt... when i cracked it open, buttery looked at it and said "have fun!". if it helps, tell the dogs i scrapped 2 sheets of paper before i got it right... i triple checked it. hell, after i cut that switch out (parts attached) i checked it again... ya, i'm kinda' anal. you want the switch? - i'm kidding...

>> This one.... I (not you!) sketched it on paper, turned it this way and that, showed it to the dogs and they couldn't figure it out either.... arg! crumple and toss.

well, i guess we can say that one didn't go to the dogs? what helped me understand what was kind of going on, was to draw each switched path individually.

>> Then Franken mentioned the problem most scanners have with pencil/paper, and I figgered at least I could get that much use out of the wasted paper. Well, scanner doesn't handle wrinkes well either.

i loath cheap scanners. decent office units seem to work better... but alas, home stuff gets job done though.

>> NO offense intended.

absolutely NONE taken. 

[Frankenamp]

OK, Stupid question time: I recycled the cap can after gutting it and stuffing it full of two 20uF, and one 10uF caps and the associated resistors- Kinda like the posted layout. The 20's go to the screen and the plate of the power tube (6GW8) and the 10 goes to the 12AX7 tube. Am I correct in assuming that I can get away with using the 10 for the preamp? I have seen other Champ schematics that show only 8uF or 10uf's in all positions.
Second Stupid question: The OT has a pretty long red lead- it was originally getting B+ from somewhere off the oscillator can that went bye-bye, and since it will be tied to the cap lead anyways- can I just use the pin #7 of the rectifier (6X4) tube as a convenient tie point for both wires? I'm not planning on using a standby switch at this juncture. I'm thinking it's a semi-elegant solution that leaves the leads long enough to add a standby switch later if I find I want one. Schematically, it dosen't seem (to my unedjumacated self) to make much difference, but I've read that some layouts have a tendency to invite more trouble (in the form of noise, hum, and other associated gremlins) and I want keep those in far abayance as possible.

Thanks in advance for your shared knowlege

[Frankenamp]

DAMN!  
OK, I reached in my little bin of 25uF caps and soldered one in place between pin #3 of my 12AX7 and ground (parallel with a 1K5 cathode resistor) with all the bendy-twisty finegeling to the leads to make the dammed thing fit... And then I check it again with my DVM (wavetek 27XT) only to find out that it's a 47uF 25V cap! (insert your favorite profanity)!!
SO, do I leave it in (or do I replace it with the correct cap)

(a quick tutorial on what it does to the corner bypass frequency would be helpful) If I'm gonna have to learn from my mistakes, I might as well maximize my learning potential

Thanks

Edit: replaced with the correctish (22uF) cap

[Frankenamp]

OK, Stupid question time: ... can I just use the pin #7 of the rectifier (6X4) tube as a convenient tie point for both wires? I'm not planning on using a standby switch at this juncture. I'm thinking it's a semi-elegant solution that leaves the leads long enough to add a standby switch later if I find I want one.

well, since no one said "no" I did it. I also am trying another trick someone suggested (and seems to work on the Duncan tonestack calculator) of putting a switch on the ground return resistor on the Bass pot. I put in a pot with a push-pull switch to effectively 'lift' the resistor.

I dithered on the cathode resistors for the 6GW8 (180, 220, & 330 ohms) and finally decided on the 220 ohm 1W value, all the schematics agreed that 50uF is the magic number, so I figured 47uF/25V was close enough fer gov't work. My fancy lighted switch that is supposed to fit the old aux plug punch out hole didn't come in yet, so I made a trip to Rat Shack, and found an el cheapo that did, and found some miniature knobs that fit the spacings that I had (it was either that, or put a couple vintage Fender knobs on the lathe and turn 'em down a bit). Once I put the switch and fuse holder in, I won't have too many more excuses to not break out the limiter lamp and see what happens.

[Frankenamp]

http://www.el34world.com/forms/valve.cgi

Low volume- gets sound out of it (just not very much).

No tubes in I got 310-0-310 =>626 out of the PT on the high side and a solid 6V on the heater side with the lightbulb limiter in the circuit. not even a flicker in the bulb...

Tubes in:
Solid 310 off pin #7 of the 6X4 once the current got through the OT windings to the plate it dropped to 296. The grid is getting 302 V.
'C' voltage point is 284V which after the 100k resistors drops to 198 @ pin 1, and 191 @ pin 6. The 6GW8 has 8V off the cathode.

I did the old plug in a cable and touch the center conductor trick- slight hum... pluged in my ipod nano as a signal source and got precious little except with the volume dimed and the tone bypass (bass pot resistor lifted by the switch, not in dwg- it was an afterthought) volume was still very low. I did notice a small jump in volume when I touched my meter to the grid connection. Is 220k too much resistance? all connections are tight, and no cold joints. I chopsticked everything I could think of, still very low volume. Any Ideas?

[Frankenamp]

OK, this things been in a box for a while and I'm trying to get it up an at em. Motivation is everything (new guitar). Old (my age) ham looked at the guts and said that the lugs of the tone pots were a leetle close to the chassis (they were- added a couple layers of electrical tape and tweaked the lugs away from the frame. <anticipation>  dug out the silvertone 6GW8,  6X4, and a chinee 12AX7 and fired it up again. Light on limiter stays unlit for the most part. Input plug doesn't buzz <ominous> Plug in ipod... Sammy finds no way to rock... <gnurrr>

More troubleshooting ahead

[DummyLoad]

Sammy finds no way to rock... <gnurrr>

post some pics?